/****************************************************************************
**
** Copyright (C) 2000-2007 TROLLTECH ASA. All rights reserved.
**
** This file is part of the Opensource Edition of the Qtopia Toolkit.
**
** This software is licensed under the terms of the GNU General Public
** License (GPL) version 2.
**
** See http://www.trolltech.com/gpl/ for GPL licensing information.
**
** Contact info@trolltech.com if any conditions of this licensing are
** not clear to you.
**
** This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
** WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
**
****************************************************************************/

#include "QCodePage437Codec.h"

static const char hexchars[] = "0123456789ABCDEF";

// Convert IBM437 character codes 0x00 - 0xFF into Unicode.
static ushort const cp437ToUnicode[256] = {
    0x0000, 0x0001, 0x0002, 0x0003, 0x0004, 0x0005, 0x0006, 0x0007,
    0x0008, 0x0009, 0x000a, 0x000b, 0x000c, 0x000d, 0x000e, 0x000f,
    0x0010, 0x0011, 0x0012, 0x0013, 0x0014, 0x0015, 0x0016, 0x0017,
    0x0018, 0x0019, 0x001c, 0x001b, 0x007f, 0x001d, 0x001e, 0x001f,
    0x0020, 0x0021, 0x0022, 0x0023, 0x0024, 0x0025, 0x0026, 0x0027,
    0x0028, 0x0029, 0x002a, 0x002b, 0x002c, 0x002d, 0x002e, 0x002f,
    0x0030, 0x0031, 0x0032, 0x0033, 0x0034, 0x0035, 0x0036, 0x0037,
    0x0038, 0x0039, 0x003a, 0x003b, 0x003c, 0x003d, 0x003e, 0x003f,
    0x0040, 0x0041, 0x0042, 0x0043, 0x0044, 0x0045, 0x0046, 0x0047,
    0x0048, 0x0049, 0x004a, 0x004b, 0x004c, 0x004d, 0x004e, 0x004f,
    0x0050, 0x0051, 0x0052, 0x0053, 0x0054, 0x0055, 0x0056, 0x0057,
    0x0058, 0x0059, 0x005a, 0x005b, 0x005c, 0x005d, 0x005e, 0x005f,
    0x0060, 0x0061, 0x0062, 0x0063, 0x0064, 0x0065, 0x0066, 0x0067,
    0x0068, 0x0069, 0x006a, 0x006b, 0x006c, 0x006d, 0x006e, 0x006f,
    0x0070, 0x0071, 0x0072, 0x0073, 0x0074, 0x0075, 0x0076, 0x0077,
    0x0078, 0x0079, 0x007a, 0x007b, 0x007c, 0x007d, 0x007e, 0x001a,
    0x00c7, 0x00fc, 0x00e9, 0x00e2, 0x00e4, 0x00e0, 0x00e5, 0x00e7,
    0x00ea, 0x00eb, 0x00e8, 0x00ef, 0x00ee, 0x00ec, 0x00c4, 0x00c5,
    0x00c9, 0x00e6, 0x00c6, 0x00f4, 0x00f6, 0x00f2, 0x00fb, 0x00f9,
    0x00ff, 0x00d6, 0x00dc, 0x00a2, 0x00a3, 0x00a5, 0x20a7, 0x0192,
    0x00e1, 0x00ed, 0x00f3, 0x00fa, 0x00f1, 0x00d1, 0x00aa, 0x00ba,
    0x00bf, 0x2310, 0x00ac, 0x00bd, 0x00bc, 0x00a1, 0x00ab, 0x00bb,
    0x2591, 0x2592, 0x2593, 0x2502, 0x2524, 0x2561, 0x2562, 0x2556,
    0x2555, 0x2563, 0x2551, 0x2557, 0x255d, 0x255c, 0x255b, 0x2510,
    0x2514, 0x2534, 0x252c, 0x251c, 0x2500, 0x253c, 0x255e, 0x255f,
    0x255a, 0x2554, 0x2569, 0x2566, 0x2560, 0x2550, 0x256c, 0x2567,
    0x2568, 0x2564, 0x2565, 0x2559, 0x2558, 0x2552, 0x2553, 0x256b,
    0x256a, 0x2518, 0x250c, 0x2588, 0x2584, 0x258c, 0x2590, 0x2580,
    0x03b1, 0x00df, 0x0393, 0x03c0, 0x03a3, 0x03c3, 0x03bc, 0x03c4,
    0x03a6, 0x0398, 0x03a9, 0x03b4, 0x221e, 0x03c6, 0x03b5, 0x2229,
    0x2261, 0x00b1, 0x2265, 0x2264, 0x2320, 0x2321, 0x00f7, 0x2248,
    0x00b0, 0x2219, 0x00b7, 0x221a, 0x207f, 0x00b2, 0x25a0, 0x00a0
};



// Convert Unicode 0x0000 - 0x00FF into IBM437.
static unsigned char const cp437FromUnicode[256] = {
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
    0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
    0x18, 0x19, 0x7f, 0x1b, 0x1a, 0x1d, 0x1e, 0x1f,
    0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
    0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
    0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
    0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47,
    0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
    0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
    0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
    0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
    0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
    0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
    0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x1c,
    '?' , '?' , '?' , '?' , '?' , '?' , '?' , '?' ,
    '?' , '?' , '?' , '?' , '?' , '?' , '?' , '?' ,
    '?' , '?' , '?' , '?' , '?' , '?' , '?' , '?' ,
    '?' , '?' , '?' , '?' , '?' , '?' , '?' , '?' ,
    0xff, 0xad, 0x9b, 0x9c, '?' , 0x9d, '?' , 0x15,
    '?' , '?' , 0xa6, 0xae, 0xaa, '?' , '?' , '?' ,
    0xf8, 0xf1, 0xfd, '?' , '?' , '?' , 0x14, 0xfa,
    '?' , '?' , 0xa7, 0xaf, 0xac, 0xab, '?' , 0xa8,
    '?' , '?' , '?' , '?' , 0x8e, 0x8f, 0x92, 0x80,
    '?' , 0x90, '?' , '?' , '?' , '?' , '?' , '?' ,
    '?' , 0xa5, '?' , '?' , '?' , '?' , 0x99, '?' ,
    '?' , '?' , '?' , '?' , 0x9a, '?' , '?' , 0xe1,
    0x85, 0xa0, 0x83, '?' , 0x84, 0x86, 0x91, 0x87,
    0x8a, 0x82, 0x88, 0x89, 0x8d, 0xa1, 0x8c, 0x8b,
    '?' , 0xa4, 0x95, 0xa2, 0x93, '?' , 0x94, 0xf6,
    '?' , 0x97, 0xa3, 0x96, 0x81, '?' , '?' , 0x98
};

QCodePage437Codec::QCodePage437Codec()
{
}

QCodePage437Codec::~QCodePage437Codec()
{
}

QByteArray QCodePage437Codec::name() const
{
    return "IBM437";
}

QList<QByteArray> QCodePage437Codec::aliases() const
{
    QList<QByteArray> list;
    list << "CP437";
    return list;
}

int QCodePage437Codec::mibEnum() const
{
    return 437;
}

QString QCodePage437Codec::convertToUnicode(const char *in, int length, ConverterState *) const
{
    QString str;
    if ( length >= 6 && in[0] == '8' && in[1] == '0' &&
         in[length - 4] == 'F' && in[length - 3] == 'F' &&
         in[length - 2] == 'F' && in[length - 1] == 'F') {

        // UCS-2 string embedded within a 437-encoded string.
        int nibble = 0;
        int value = 0;
        int digit;
        in += 2;
        length -= 6;
        while ( length-- > 0 ) {
            char ch = *in++;
            if ( ch >= '0' && ch <= '9' ) {
                digit = ch - '0';
            } else if ( ch >= 'A' && ch <= 'F' ) {
                digit = ch - 'A' + 10;
            } else if ( ch >= 'a' && ch <= 'f' ) {
                digit = ch - 'a' + 10;
            } else {
                continue;
            }
            value = value * 16 + digit;
            ++nibble;
            if ( nibble >= 4 ) {
                str += QChar( (ushort)value );
                nibble = 0;
                value = 0;
            }
        }

    } else {

        // Regular 437-encoded string.
        while ( length-- > 0 ) {
            str += QChar((unsigned int)cp437ToUnicode[*in++ & 0xFF]);
        }

    }
    return str;
}

QByteArray QCodePage437Codec::convertFromUnicode(const QChar *in, int length, ConverterState *) const
{
    QByteArray result;
    unsigned int ch;
    char *out;

    // Determine if the string should be encoded using the UCS-2 hack.
    bool non437 = false;
    for ( int posn = 0; !non437 && posn < length; ++posn ) {
        ch = in[posn].unicode();
        if ( ch >= 0x0100 ) {
            non437 = true;
        } else if ( cp437FromUnicode[ch] == '?' && ch != '?' ) {
            non437 = true;
        }
    }
    if ( non437 ) {
        // There is a non CP437 character in this string, so use UCS-2.
        result.resize( length * 4 + 6 );
        out = result.data();
        *out++ = '8';
        *out++ = '0';
        while ( length-- > 0 ) {
            uint ch = in->unicode();
            ++in;
            *out++ = hexchars[ (ch >> 12) & 0x0F ];
            *out++ = hexchars[ (ch >> 8) & 0x0F ];
            *out++ = hexchars[ (ch >> 4) & 0x0F ];
            *out++ = hexchars[ ch & 0x0F ];
        }
        *out++ = 'F';
        *out++ = 'F';
        *out++ = 'F';
        *out   = 'F';
        return result;
    }

    // If we get here, we can guarantee that the string only contains
    // valid CP437 code points between 0x0000 and 0x00FF.
    result.resize( length );
    out = result.data();
    while ( length-- > 0 ) {
        *out++ = (char)cp437FromUnicode[in->unicode()];
        ++in;
    }
    return result;
}

